1. Field of the Invention
The present invention is related to an improved structure for a seat supporting frame of a chair, especially is related to having a horizontal a support, front leg, a vertical support piece, and a stop abutment to be held together secure and tightly, and thereby preventing the chair from loosening because of having a heavy people sitting in the chair.
2. The Prior Arts
With reference to FIG. 1 and FIG. 1A, which is the partial enlarged view showing the horizontal support A, the front leg B, the vertical support piece C, and the stop abutment C1 in the conventional folding chair, the seat supporting spots of the conventional folding chair are located between a seat D and a back leg E, the seat D and the stop abutment C1, the seat D and the horizontal support A. So the joining together and interactions between the four parts is important.
It is observed that the stop abutment C1 connected to the vertical support piece C of the front leg B would be fractured or moved to the outer portion of the horizontal support A easily, because of the seat D having to support a person with a heavy load, and the fact that typically people changing their sitting postures constantly. If the above situation is prolonged for an extended duration, the joining together between the seat D, the front leg B, and the back leg E of the chair will be loosened, so that the stop abutment of the chair abutting on the horizontal support A will be fractured and becomes useless. It is another disadvantage that the chair will not be folded smoothly towards the inner side of the front leg B when the stop abutment C1 is moved to the outside.
In addition, the horizontal support A of the typical conventional folding chair is formed with the two ends bent into a wavy shape. The wave crest section of one end is welded to the curled edge B1 along the circumference of the front leg B; and the wave trough section is extended and welded inside the channel B2 of the front leg B. The horizontal support A is connected to the front leg B by means of the two wavy shaped ends of the support. The welded portion between the horizontal support A and the front leg B is not flat but is curved; therefore, it is more difficulty to weld it than to weld flat surfaces, saying nothing of the worker's inadequate welding technique. As a result, some folding chairs may be of unacceptable quality. The horizontal support A would not able to support the seat D if it is loosened. Additionally, it is very dangerous for the person sitting if the stud C2 above the stop abutment C1 is loosened as well.
With reference to FIG. 1B showing another kind of conventional folding chair, a horizontal support F of the chair with the two ends of which are bent and welded also at the inner side of the front leg G, is also not formed with a curved section for keeping the stop abutment H from moving outside. As a result, the above chair has the same disadvantage as the previous one having the seating frame to be fractured.